The present invention relates to a heat exchanger, in particular for exhaust gas cooling.
During the combustion of fuel in internal combustion engines, exhaust gas arises. Part of the exhaust gas is cooled in heat exchangers, in particular in exhaust gas heat exchangers, and is subsequently admixed with the charge air of the internal combustion engine and supplied to the internal combustion engine.
Various designs of welded or soldered heat exchangers, in particular exhaust gas heat exchangers, as tube-bundle or stacked disk systems are known. Known heat exchangers have, in particular, thin-walled housings. These require additional holding elements for fastening to the engine or to the vehicle. This entails not only additional costs, but also an increased space requirement. When flowing through the heat exchangers, in particular the exhaust gas heat exchangers, the tubes of the heat exchanger experience thermal longitudinal extension and thermal transverse extension. For this reason, the housing has a mostly flexible configuration. Due to this flexibility of the housing, coolant connection pieces, which ensure the inflow and outflow of a cooling medium, are connected in a flexible manner to the engine block of an internal combustion engine or to the engine-side water supply.
DE 102 18 521 A1 discloses an exhaust gas heat exchanger, in particular for motor vehicles with exhaust gas recirculation (AGR), which consists of a housing casing for a coolant and of a tube bundle, through which exhaust gas flows and around which the coolant flows and which is received in the housing via tube bottoms, the tube bundle, tube bottoms and housing forming a force flux closed on itself, a push fit being arranged in the force flux. The ends of the tubes are fastened in a tube bottom which is itself welded to the housing casing. The housing casing has a push fit. An outer ring overlaps an inner ring and with the latter forms a slide fit. The slide fit is sealed off outwardly, that is to say with respect to the atmosphere, by means of two O-rings, so that no coolant can escape outward.
DE 102 04 107 A1 discloses a heat exchanger, in particular exhaust gas heat exchanger for motor vehicles, with a tube bundle, through which a gaseous medium flows and around which a liquid coolant flows and the tubes of which are received with their tube ends in tube bottoms and are connected to these in a materially integral manner, and with a housing casing which surrounds the tube bundle and is connected on the end face to the tube bottoms in a materially integral manner and through which the coolant flows, the tube bottoms and housing casing being produced from a heat-resistant and corrosion-resistant metallic alloy, the housing casing having at least one peripheral expansion bead. This bead gives the housing casing sufficient elasticity in the longitudinal direction of the tubes, so that the housing casing, by elastic extension, can follow the greater extension of the exhaust gas tubes, without an inadmissible deformation or an impairment of the weld seam connection between tubes and bottom and bottom and housing occurring in this case.
Furthermore, DE 102 24 263 A1 discloses an exhaust gas heat exchanger, in particular for motor vehicles with exhaust gas recirculation, consisting of a housing with a housing casing for a coolant and of a tube bundle, through which exhaust gas flows and around which the coolant flows and which is received in the housing via a first and a second tube bottom, the first tube bottom being connected firmly to the housing and therefore forming a fixed bearing for the tube bundle, and the second tube bottom being designed as an elastic plastic bottom. The plastic bottom, on account of its modulus of elasticity, is capable, by elastic deformation, of following certain extensions, such as occur in the tube bundle when the exhaust gas heat exchanger is in operation. This leads to an elastic bulging or deformation of the plastic bottom, with the result that inadmissible stresses in the components are avoided.